Maybe, maybe not, (how specific is that?)

Gamers DEFINITELY should NOT use the automated memory freeing feature, (set the threshold to 0). You MAY want to free some memory just before you start Quake, etc. However, if you free too much memory you might find it impacts the game - you'll notice a little hard disk activity from time to time after you start the game, (which of course could be fatal if you've got some asshole with a bazooka on your tail just at that moment).

The "right" amount of memory to have free is difficult to judge. As a rule of thumb, I'd recommend aiming to have about the same amount that was free when you started Windows just before you start a game.

Without a doubt the best way to improve the performance of a game is to tweak your Windows settings. Start by eliminating any unneeded junk from the startup sequence, (particularly if you find you don't have much free memory after you start Windows), then look for tweaks for your graphics adaptor. File cache and virtual memory settings also make a big difference if used intelligently, particularly if you've got SCSI disks, (in fact regardless of what disks you have, you should definitely tweak file cache settings if you haven't already done so -- use Cacheman if you don't want to do it manually).

If you think your system is pretty well configured already, tweaking it 'til you're blue in the face is pretty pointless. If your basic hardware is good, but your performance is pretty sucky, tweaking can make a big difference. Remember the aim is not to free as much memory as possible, (I can't stress this enough, since its the most common mistake people make) -- its to squeeze every last ounce of juice out of the cpu, graphics card, disk and memory combined.

A quick lesson in memory usage:
All operating systems read and write information to and from memory to a file, (or files), on hard disk if there is not enough room to store all the required information in physical memory. For a gamer, the key is to minimize reading/writing to this, (or these), "swap" file(s). To do this, you want the game and all the "system" information that is required to run the game to be in memory, not "swapped" out to disk. Freeing tons of memory before you start a game just writes the "system" information to disk, so it will be read back in when the game needs it. If you have very little memory available before you start the game, chances are part of the game itself will be swapped out, so it will be read back in when needed. If you tweak your system, and you still don't have much memory available before you start the game, its time to start thinking about buying more RAM. If you're running the game, and its chewing memory, that's okay -- most graphics intensive games will use all the memory they can get. If it uses all your memory, then it will start swapping as needed. If this is the case, virtual memory tweaking can help, ("virtual memory" has more than one meaning, but here I'm referring to the swap file settings -- this is not the most correct use of the term, but it is widely used in Windows parlance). Generally, its the graphics themselves that eat memory. You can often get great improvements by adding video memory to your graphics adaptor, or buying a more powerful graphics adaptor, (but you need to keep in mind that buying a really powerful graphics adaptor is a waste of money if your cpu, motherboard and system bus can't keep up with it).

One of the best places to start looking at tweaks: http://members.aol.com/axcel216

I presume you've already started reading the FAQs: http://www.jfitz.com/software/RAMpage/RAMpage_FAQS.html

You might find some good gaming specific info and links here: http://www.tweakfiles.com

One other thing, if you play Quake over a low speed internet connection, there are tweaks for MTU size and other network settings that can help squeeze that last ounce of speed out of the connection.

Its difficult to be more specific, as the "right" thing to do varies depending on the exact configuration of the machine, and the game you're playing.